My differential (ratio 3.27) unexpectedly went out on my 2002 C230K Coupe at 37,000 miles. I have the option of purchasing a 2004 C230K, 6-speed manual transmission differential (ratio 3.46) from a salvage vehicle that was totaled when hit in right side rear. They claim the differential was not affected. I have also heard that many others parts are designed to failed, when being hit from the rear, so that the differential should not be affected. The differential from the 2004 is from a 1.8L, however, the sub frames are the same. I have been told that if I install the 3.46 in place of the 3.27, the computer speedometer would not be registering the correct speed. Is this true for manual transmission and if so, how do I remedy this?